Performance Estimation of Bycatch Reduction Devices for Coastal Shrimp Beam Trawl Using Dynamic Modeling

The purpose of this study is to identify the shape of the net spread out underwater and bycatch reduction performance for target fish species when applying the four types of bycatch reduction devices of the bycatch management regulations to shrimp beam trawl. To this end, shrimp beam trawl was modeled as a mass-spring, and the size of the target fish species was investigated and compared with the size of the escape hole. As a result, the shape and size of the escape hole spread out of each bycatch reduction device was changed from that described in the regulations, and some had a reduced codend volume. In addition, the escape holes of the inclined-upward escape device, inclined-downward escape device, and wall-type-downward escape device were larger in height and width than the body height and width of the fish mainly caught in the shrimp beam trawl, while the escape hole of the conical-downward escape device was relatively smaller than the body width or height of the target fish. Therefore, it is thought that a study analyzing the underwater spreading out shape of bycatch reduction devices through numerical modeling can be an effective means for examining the design validity in advance.